Miniaturized high-frequency transformer



' P 1970 :KAZUTOMdlWATA 3,528,047

MINIATURIZED HIGH-FREQUENCY TRANSFORMER Filed May 9, 1969 I INVENTOR KHZLLTDHO IWH TR ATTORNEY 5 United. States Patent US. (3]. 33683 3 ClaimsABSTRACT OF THE DISCLOSURE A miniaturized high-frequency transformercomprising: a cap core having an adjusting magnetic core at its centerand an adjustment groove at its closed end; a core supporter having ahole at its center and another adjustment groove at its closed end; aterminal board member having coils wound thereon and a through tappinghole, the core supporter being in threaded engagement with the tappinghole so that the core supporter is firmly and adjustably coupled withthe terminal board member and the resulting assembly is covered with thecap core with the adjusting magnetic core inserted into the hole in thecore supporter; and a shield case for substantially enclosing theassembled transformer structure, whereby the inductance of thetransformer is adjustable on either one of the opposite sides of thestructure.

The present invention relates to a miniaturized highfrequencytransformer used for example, in a miniaturized television receiver andis intended to provide a miniaturized transformer structure which hashigh performance and the inductance of which can be adjusted on eitherone of the opposite sides of the structure so that the transformerstructure can be assembled on a printedcircuit board.

Generally, in case the operating frequency of a highfrequencytransformer is not so high, a cap-shaped ferrite core which covers coilsis used in order to prevent quality factor (Q) of the transformer frombeing lowered due to the proximity effect by a shield case, and inalmost all the conventional high-frequency transformers, the arrangementhas been such that coils are wound on a ferrite core which isdrum-shaped and the resulting core assembly is adjustably covered with acap-shaped core which is provided with an adjusting groove at its closedend and is further threaded on its outer periphery for the purpose ofmoving the cap-shaped core to adjust the inductance of the transformer.

In such an arrangement as mentioned above, the adjustment of theinductance of a high-frequency transformer is performed only on one side(e.g., at the top portion) of the transformer, so that a completedminiaturized device such as a miniaturized television receiver must haveincluded a space necessary for performing adjustment of the inductanceof such a transformer, thus obstructing miniaturization of completeddevices which include such a transformer.

The present invention relates to a high-frequency trans- ,former freefrom the disadvantages mentioned above.

The present invention will be explained referring to the accompanyingdrawings illustrating an embodiment of the present invention, in which:

FIG. 1 is a half cross-sectional front view of a high frequencytransformer in accordance with an embodiment of the present invention;

FIG. 2 is a perspective view of the major parts of the transformer shownin FIG. 1 is a disassembled state; and

FIG. 3 is a perspective view of a cap-shaped core which is used in thetransformer.

In the drawings, numeral 1 designates a terminal board member in thecenter of which a hole 2 is bored to define a tapping cylindrical walland which, at its upper portion, has a winding section 4. Coils 3 arewound on the section 4. The hole 2, hereafter referred to as tappinghole, of the terminal board member 1 is.bored in the form of a throughhole, and a shaft section 6 of a core supporter 5 made of athermoplastic resin in a threaded engagement with the tapping hole 2 bymeans of self-tapping technique. Namely, a plurality of ridges 7 areprovided on the periphery of the shaft section 6 in the axial directionof the shaft section 6 so that the ridges 7 may be tapped when the coresupporter 5 is adjustably fitted into the tapping hole 2 bysimultaneously turning and depressing the core supporter 5. And at thebottom of the shaft section 6 of the core supporter 5 an adjustmentgroove 8 is formed, on a flange section 9 of the core supporter 5 twoprotuberances 10 are formed, and a hole 11 is defined extending throughthe flange section 9 and part of the shaft section 6. The core supporter5 having such a construction as mentioned is coupled with a cap core 13which is in the form of a hollow cylinder and has an adjusting magneticcore 12 extending axially of the cap core 13 and located at the centerof the cylinder. Funnel-shaped holes 20 tapering downwardly as viewed inFIG. 3 are defined in the top plate of the cap core 13 at positions tobe engaged with the protuberances 10 of the core supporter 5 so that theprotuberances 10 may be fixed into the holes 20 and fused and unitedwith each other by means of thermal welding. The adjusting magnetic core12 of the cap core 13 is inserted into the hole 11 of the core supporter5. At the top of the cap core 13 another adjustment groove 14 is formed.

And a shield case 15 wholly covers the resulting assembly including themembers as shown in FIG. 2. At the bottom of the shield case 15 earthterminals 16 is formed and at the top of the shield case 15 anadjustment groove 19 corresponding to the groove 14 in the cap core 13is formed. Further, one end of each of terminal pins 17 is buried in theterminal board member 1 and recesses 18 for lead line are provided forin the terminal board member 1.

In the miniaturized high-frequency transformer made according to thepresent invention as mentioned above, when the operating frequency hasto be adjusted by mov ing the cap core 13 upward or downward, theadjustment can be accomplished, when necessary, not only at the top ofthe transformer using the adjustment groove 14 of the cap core 13 butalso at the bottom of the transformer using the adjustment groove 8 ofthe core supporter 5 through the tapping hole 2 in the terminal boardmember 1, and even if the miniaturized transformer is assembled on aprinted-circuit board, for example in a miniature television receiver,definition of a through hole in the printed-circuit board will suflicefor a satisfactory adjustment of the inductance of the transformer dueto the fact that on either one of the two opposite sides of thetransformer, i.e., through the adjustment groove 14 or 8 or both,inductance adjustment is possible. Thus, miniaturization of a completeddevice can be attained.

Further, the core supporter 5 is madeof a thermoplastic resin, theprotuberances 10 are formed on the top 9 of the core suporter 5 and bothare coupled by means of thermal welding after the protuberances 10 havebeen fixed in the holes 20, so that the assembly can be accomplishedeasily and fixedly.

Further, since a plurality of ridges 7 are provided on the periphery ofthe shaft section 6 of the cores supporter 5 in the axial direction sothat the ridges 7 are tapped by the tapping hole 2 in the terminal boardmemberIby self-tapping technique, the threaded engagement between thecore supporter 5 and the terminal board member 1 is stable, and smoothupward and downward movement of the cap core 13 can be accomplished.Thus, the present invention can make a great contribution to the fieldof miniaturization of electronic devices.

What is claimed is:

1. A miniaturized high-frequency transformer comprising: a terminalboard member having a through tapping hole at its center extending inits axial direction and coils wound on one end of said terminal boardmember; a core supporter having an adjustment groove at its closed endand a hole at its center extending in its axial direction and adapted tobe in threaded engagement with said tapping hole of said terminal boardmember; a cap core having an adjustment groove at its closed end and anadjusting magnetic core at its center extending in its axial direction,said adjusting magnetic core being inserted into said hole in said coresupporter; and a shield case covering the resulting assembly.

2. A high-frequency transformer as claimed in claim 1., in which saidcore supporter is made of a thermoplastic resin, at least twoprotuberances are formed at an open end of said core supporter so thatsaid protuberances are fixed into holes prepared at said closed end ofsaid cap core the number of which corresponds to the number ofprotuberances, and said core supporter and said cap core are coupledwith each other by means of thermal welding.

3. A high-frequency transformer as claimed in claim 1, in which saidcore supporter is made of a thermoplastic resin, a plurality of ridgesare formed on a shaft section of said core supporter for forming threadsthereon in the axial direction so that the shaft section of the coresupporter is in threaded engagement with said tapping hole in saidterminal board member by simultaneously turning and depressing said coresupporter so as to adjustably fit the latter into said tapping hole toeffect a self-tapping operation.

References Cited UNITED STATES PATENTS 2,318,415 5/1943 Patzschke et al.336-136 2,435,630 2/1948 Ketcham 33687 XR 2,717,984 9/1955 Hale et al.33683 XR 2,823,359 2/1958 Wentworth 336131 XR 3,227,980 1/1966 Roser336-83 XR 3,309,640 3/1967 Oshima 33683 XR THOMAS J. KOZMA, PrimaryExaminer US Cl. X.R. 33687, 136

